1. Field of the Invention
This invention relates to wind turbines for generating electrical power, particularly to vertical axis wind turbines, and more particularly to such turbines having means for preventing catastrophic failures in high winds.
2. Brief Description of the Prior Art
Wind Turbines provide a source of electrical power as an alternative to fossil fuels to help reduce gaseous emissions and other environmental problems. Wind turbines also provide electrical power in remote areas where power lines have not been strung. Accordingly, numerous wind turbines have been installed in high wind areas in the United States and other countries.
Wind turbines have either horizontal axes or vertical axes of rotation, with each type having different advantages and disadvantages. Vertical axis turbines have, among other advantages, little or no need for a tower on which to mount the turbines. The turbine, gearing electrical generators and the like can generally be mounted at ground level.
Most wind turbines are subject to possible damage from excessively high winds. Vertical axis turbines are less vulnerable to damage from high winds because such turbines are not usually mounted on towers that can be blown over. However, high winds can damage vertical axis turbines by causing them to run at excessively high speeds (RPM), which can cause catastrophic failure of the rotor, gearing, etc.
It is known to provide speed limiters or governors for wind turbines to reduce the risk of damage from high winds and excessively high speed rotation of the turbines. For example, U.S. Pat. No. 5,425,619 to Aglor discloses a horizontal axis turbine having spring-loaded gate flaps which open responsive to predetermined levels of air pressure to spill air through outlets instead of across the air-engaging blades in the turbine. U.S. Pat. No. 3,856,432 discloses a vertical axis turbine having leaves made of resilient material which are unfolded by centrifugal forces at predetermined rotational speeds to interfere with air that would otherwise cause the rotor to speed out of control. U.S. Pat. Nos. 591,962; 1,586,914 and 4,004,861 also disclose systems for controlling the speed of wind turbines.
An improved means is needed for reducing the risk to vertical axis wind turbines from high winds.
A low cost, reliable wind turbine is desired which includes means for reducing the possible risk of excessively high speed operation.
A vertical axis wind turbine is needed that will not destroy itself in high winds.
A wind turbine is also desired that is economical to manufacture.